In Vitro Circadian Clock Gene Expression Assessments in Mesenchymal Stem Cells from Human Infants: A Pilot Study

Background: Exposure to intrauterine obesity can disrupt clock gene rhythmicity in animal models. The aim of this pilot study was to determine if maternal obesity alters rhythmic expression of core clock in mesenchymal stem cells (MSCs) from umbilical cords of human infants born to mothers with obesity (Ob-MSC) vs. normal weight (NW-MSC). Methods: We compared in vitro rhythmic expression patterns of core clock (BMAL1, CLOCK, PER2) and clock-output (NR1D1), components in undifferentiated Ob-MSCs (n = 3) vs. NW-MSCs (n = 3). MSCs were harvested every 2 h, following a dexamethasone shock, for 30 h. Adipogenesis or myogenesis was induced in vitro and markers of adipogenesis and fat storage were assessed, respectively. Results: We detected significant rhythmicity in expression patterns of BMAL1, PER2, and NR1D1 at the group level in Ob- and NW-MSCs (p < 0.05). PER2 oscillatory amplitude was 3-fold higher in Ob-MSCs vs. NW-MSCs (p < 0.006). During adipogenesis, Ob-MSCs had higher PPAR gamma protein content (p = 0.04) vs. NW-MSC. During myogenesis, Ob-MSCs had higher saturated triacylglycerols (p = 0.04) vs. NW-MSC. Conclusion: Rhythmic expressions of BMAL1, PER2, and NR1D1 are detectable in undifferentiated MSCs. Higher PER2 oscillatory amplitude was paralleled by higher markers of fat storage during differentiation in Ob-MSCs vs. NW-MSCs, and supports that the core clock and cellular metabolism may be linked in infant MSCs.